Binocular indirect ophthalmoscopy offers several advantages over direct ophthalmoscopy, including stereopsis and a much enlarged field of view and depth of field. However, the usefulness and flexibility of binocular indirect ophthalmoscopy has been generally restricted to use in the examination of eyes with substantially clear opacity. Other techniques using infrared scanning laser ophthalmoscopes or infrared fundus cameras are generally employed to examine eyes with media opacity.
For example, scanning laser ophthalmoscopy (SLO) using infrared illumination is preferably used to examine eyes with nuclear sclerotic cataracts or mild vitreous hemorrhage, and in combination with indocyanine green angiography (ICG) to examine the choroidal layer, lesions and subretinal membranes and scars of the eye. SLO uses a low power, focused laser beam, typically Helium-Neon ("He--Ne"), to scan the size of the aperture through which the reflected radiation is collected. The advantages of SLOs as well as those of infrared fundus cameras are well known to those skilled in the art. Unfortunately, SLOs as well as infrared fundus cameras are prohibitively costly for most clinicians and lack the accustomed stereopsis, which is helpful in evaluating the topography of the fundus features. For these reasons, a need has arisen for an improved binocular indirect ophthalmoscope having comparable capabilities to those of SLOs or infrared fundus cameras, but yet which is relatively inexpensive.